Computes the difference between two instants, as measured in the units
of this field. Any fractional units are dropped from the result. Calling
getDifference reverses the effect of calling add. In the following code:

Computes the difference between two instants, as measured in the units
of this field. Any fractional units are dropped from the result. Calling
getDifference reverses the effect of calling add. In the following code: